looking for help finding his son's killer. Incredibly, his son lost his life because of a rivalry between fans of the dodgers and the giants. And this isn't the first case. In california tonight, here's abc's aditi roy. Today, I'm making a plea to the public, asking that anyone who may have witnessed the incident, to come forth. Reporter: A father makes a plea for information in his son's death. It was supposed to be a family night at the ballpark. 24-year-old jonathan denver was stabbed to death near at&t stadium after police say his group got into an argument with a group of giants fans after the game. There was a back and forth about the giant/dodger rivalry, which deteriorated into a physical fight. Reporter: San francisco police arrested 21-year-old michael montgomery, then released him saturday night, citing insufficient evidence. It's not the first time violence erupted from dodgers/giants rivalry. In 2011, giants fan bryan stow suffered a traumatic brain injury after being beaten by two men dressed as dodgers gear following a game between the two teams in los angeles. At thursday night's giants game against the dodgers, a moment of silence for denver. His father asking for answers. The giants released a statement, expressing sadness over denver's death, adding, there is no place in your community for this type of violence.

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